To provide a semiconductor plant capable of securing a duct lower space in a utility space without causing curvature, etc., of a floor material, etc., at the time of depositing enlarged and weight increased manufacturing apparatuses.

This plant is constituted of a main manufacturing area and a core part 40 erected on both sides or one side of this main manufacturing area, the main manufacturing area is furnished with a clean room 20, a chamber formed on the ceiling side of this clean room, a floor material 24 laid on the floor side of the clean room 20, a utility space 25 formed on the lower side of this floor material 24 and a shaft for clean air circulation to communicate this utility space 25 and the chamber to each other. In this semiconductor plant, the clean room 20 has a passage 21 constituted of a member having a more load withstanding property than the floor material 24 along a boundary with the core part 40.